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x86/mce/mcelog: Use xchg() to get and clear the flags

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Using xchg() to atomically get and clear the MCE log buffer flags,
streamlines the code and reduces the text size by 20 bytes.

  $ size dev-mcelog.o.*

       text	   data	    bss	    dec	    hex	filename
       3013	    360	    160	   3533	    dcd	dev-mcelog.o.old
       2993	    360	    160	   3513	    db9	dev-mcelog.o.new

No functional changes intended.

Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
Reviewed-by: Sohil Mehta <sohil.mehta@intel.com>
Link: https://lore.kernel.org/r/20241025024602.24318-2-qiuxu.zhuo@intel.com
This commit is contained in:
Qiuxu Zhuo 2024-10-25 10:45:53 +08:00 committed by Borislav Petkov (AMD)
parent 8198375843
commit 325c3376af
1 changed files with 2 additions and 9 deletions
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11
arch/x86/kernel/cpu/mce/dev-mcelog.c
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@ -264,15 +264,8 @@ static long mce_chrdev_ioctl(struct file *f, unsigned int cmd,
return put_user(sizeof(struct mce), p);
case MCE_GET_LOG_LEN:
return put_user(mcelog->len, p);
case MCE_GETCLEAR_FLAGS: {
unsigned flags;
do {
flags = mcelog->flags;
} while (cmpxchg(&mcelog->flags, flags, 0) != flags);
return put_user(flags, p);
}
case MCE_GETCLEAR_FLAGS:
return put_user(xchg(&mcelog->flags, 0), p);
default:
return -ENOTTY;
}